Insect repellent composition



Patented May 6, 1947 INSECT REPELLENT COMPOSITION Bernard V. TravisandHoward A. J ones Orlando, Fla.; dedicated to the free use of the Peoplein the territory of the United States No Drawing. Application May 18;1944, Serial No. 536,110

2 Claims. (01. 167-30) (Granted under the act of March 3, 1883, asamended April 30, 1928; 370 0. G. 757) 1 This application is made underthe act of March 3, 1883, as amended by the act of April 30, 1928, andthe invention herein described, if patented, may be manufactured andused by or for the Government of the United States of America forgovernmental purposes without; the payment to us of any royalty thereon.

We hereby dedicate th invention herein described to the free use of thepeople in the territory of the United States to take effect on thgranting of a patent to us.

This invention relates to an improved insect repellent composition, andhas among its objects the provision of such composition which iseffective and long-lasting when applied to the skin.

Many liquid repellents are known which, when applied to the skin. willrepel insects for varying lengths of time. These repellents are.however, limited in the length of time they will protect. since they aresubject to absorption by the skin and to being readily rubbed off.

According to this invention, it has been found that a compositioncomprising a liquid repellent incorporated in powdered zinc oxide givesmuch longer repellency to insectsthan would be expected from the amountof'repellent contained in the composition. In fact, the length of timethe composition will protect a ainst biting insects is actually greaterthan that ail'orded by an amount of the liouid repellent equal to thatof the whole composition. Also, this composition is not as easily rubbedoff as is a correspondin liquid preparation when used alone. It adheresto the skin well and after a short time has no oily. a pearance orfeeling. 'The composition is therefore particularly useful in protectingmen in movement through insect-infested areas.

The proportion found most suitable for use is approximately 1 part byweight of the liquid repellent incorporated in about 1 part by weight ofthe powdered zinc oxide. These amounts give a cream or paste-likecomposition. With most of the liquid repellents tested, the compositionThe following formulas will serve to illustrate some examples of thecomposition:

Formula '1 Parts by weight Dimethyl phthalate 1 Zinc oxide 1 Formula 2Parts by weight Dimethyl p h 36 2-ethyl-l,3-hexanediol -4.-- 9 Calciumstearate 3 Zinc oxide 52 Formula 3 Parts by weightp-Iso-propylphenylethyl alcohol 44 Zinc oxid 56 The above are citedmerely as examples, and it is not to be inferred that other liquidrepellents and other proportions cannot be used.

has excellent physical properties for application to the skin. With afew liquid repellents, there is a slight tendency toward separation ofliquid on long standing. In such cases, howeverf the addition of a smallproportion of calcium stearate or other metallic stearate stabilizes thecomposition without in any way aiiecting its repellency.

The composition is preferably prepared" by adding powdered zinc oxide tothe liquid repellent slowly with suitable mixing. When all the zincoxide has been added, the composition may be further mixed with aspatula on a glass plate, ground in a mortar, or by other suitabl meansmade intoa homogeneous mixture.

In Formulas 1 and the insect repellent properties of the dimethylphthalate and the 2-ethyl- 1,3-hexanediol are well known. However, in sofar as known to the present inventors, the insect repellent propertiesof the p-iso-propylphenylethyl alcohol of Formula 3 have not heretoforebeen discovered.

The composition of this invention has beenv tested by the usual methodused in testing insect repellents. .This was done by applying l4teaspoonful of the material to be tested to the fore-v arm from wrist toelbow and exposing the arm to a large number of hungry mosquitoes orother biting insects. The time elapsing until the first bite wasrecorded. The results obtained with the three examples of ourcomposition cited above against Aedes aegypti and Anophelesquadrimaculatus (malaria carrier) are presented in the table incomparison with simultaneous results obtained with the same liquidrepellents alone.

. The increase of repellenttimeJalioraed-LLEHQ; compositions of thisinvention is very striking;

Even though the compositions contain only about 45 to 50 percentrepellent, they afiord protection against bites for a muchlonger periodthan the repellents alone. Zinc oxide alone has noinsect repellentaction.

This invention is not limited to the foregoing examples.

rated in zinc oxide in the same way with similar increases in repellenttime. Among these are the ternary solution of 6 parts dimethylphthalate,

zinc oxide very satisfactory results have also beenobtained withformulas in whicirt part.

- of liquid repellent m incorporated in 3 parts of zinc oxide and. inwhich-3:12am otl nnliren k A number of other liquid repellents andmixtures of repellents have been incorpo- 2 parts oi!2-ethyl-1,3-hexanediol, and 2 of n-butyl mesityl oxide oxalate. I

Repellents which are solid or semi-solid at room temperature may also beemployed in preparing the composition, by first dissolving them in arepellent or non-repellent liquid and then incorporating the solution inthe powdered zinc oxide,

It has also been found that compositions. comprising liquid repellentsincorporated in powdered calamine and mixtures of calamine and zincoxide give increased protection against insects,

but zinc oxide is preferable.

Although the preferred compositioncomprlses approximately 1 part liquidrepellent to'1 part lent were incorporated mlpart oi zineoxflfik It ismerely preferred that the proportionssuch as to give the desiredpaste-like or creamy" consistency to the composition.

Having thus described the invention, what is claimed is: V

1. An insect repellent composition comprisin p-iso-propylphenylethylalcohol incorporated in zinc oxide in such amounts as to form apastelike composition.

2. A method of repelling insects comprising applyingp-iso-propylphenylethyl alcohol to the skin. a

BERNARD v. TRAVIS. HOWARD A. JONES.

/ REFERENCES crrnn The following references are 01' record in the fileof this patent: I v

' UNITED STATES PATENTS.

Number Name Date U 593L485 caprio et a1. Oct. 24,1983

